Shrouded band-pass filter for oil well

ABSTRACT

Generally, embodiments described herein take the form of a shrouded band-pass filter that ensures liquid flow past the filter while reducing or minimizing gas contact with the filter. A shroud encircles the band-pass filter and is affixed to a dip tube (to which the band-pass filter is also affixed). The shroud and band-pass filter are contained within tubing within the oil well. As the pump operates, a fluid and gas mixture is drawn into the tube by operation of the pump. Gas may exit the tubing through vents while the fluid flows downward within the tubing. Fluid flows around the shroud and thus past the band-pass filter, before entering a dip tube via a strainer positioned within the shroud and above the filter. The dip tube permits the fluid to flow upward and, ultimately, out of the oil well as the pump operates.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a nonprovisional application of and claims thebenefit of U.S. Provisional Patent Application No. 63/236,644, filedAug. 24, 2021, and titled “Shrouded Band-Pass Filter for Oil Well,” thedisclosure of which is hereby incorporated herein by reference in itsentirety.

FIELD

The described embodiments relate generally to shrouded band-pass filtersin oil wells. More particularly, the present embodiments relate to theuse of a shroud about a band-pass filter to direct fluid flow past thefilter during operation of a pump in an oil well.

BACKGROUND

In oil wells with reciprocating pumps, gas problems can cost a companyvaluable time, money and resources. The presence of gas in the pumpingzone causes various problems like gas lock, gas pound, and gasinterference, resulting in reduced pump efficiency and pump failures. Toovercome these problems, down hole gas separators, such as oil anchors,gas anchors, or mud anchors, are used to divert the gas away fromentering the pump intake and thus reduce pump failures and improve thepump efficiency.

Band-pass filters may be used with reciprocating pumps to alleviateproblems associated with paraffin, asphaltenes, emulsions, and certainscales associated with the production of fluid from reservoirs. Moreparticularly, band-pass filters may guide or control crystalpolymorphism in oil. Band-pass filters convert a passive energy sourceto a spectral energy pattern tuned to be resonant with different typesof molecular oscillations pertinent to oil. Tuned energy patternsconvert problematic insoluble crystals to more thermodynamically stableand soluble crystals. The band-pass filter may be positioned upstreamfrom the reciprocating pump.

SUMMARY

In embodiments, the disclosure provides down hole gas separators for usein an artificial lift system. Example down hole gas separators include ashrouded band-pass filter that can enhance treatment of production fluidfrom the oil well before the fluid enters the pump. The shroudedband-pass filter may be included in a dip tube assembly of the gasseparator. Methods for treating production fluids using these down holegas separators are also disclosed herein.

Some conventional artificial lift systems employ a band-pass filter toalleviate problems associated with paraffin, asphaltenes, emulsions, andcertain scales associated with the production of fluid from reservoirs.The band-pass filter may be positioned upstream from the pump and insome cases may be included in a down hole gas separator. The band-passfilter relies on fluid flowing past it to operate. The more fluid fromthe oil well that flows past the band-pass filter, the better itoperates. However, some conventional down hole gas separators areconstructed such that the fluid flow path runs only partially past theband-pass filter, thereby reducing its efficiency and usefulness.

Generally, embodiments described herein take the form of a down hole gasseparator including a shrouded band-pass filter that ensures liquid flowpast the band-pass filter while reducing or minimizing gas contact withthe filter. As compared to some conventional down hole gas separators,the down hole gas separators disclosed herein can provide a fluid flowpath that directs more of the fluid entering the gas separator past theband-pass filter. In some cases, the shroud of the band-pass filter canalso help to limit the gas content of the fluid that flows past theband-pass filter.

One embodiment described herein takes the form of a gas separator foruse with a reciprocating pump in a well, comprising: a tube; a plugcapping a lower end of the tube; a dip tube in fluid communication withthe reciprocating pump, at least a portion of the dip tube positionedwithin the tube; a strainer at an opposing end of the dip tube from thereciprocating pump; a band-pass filter attached to an end of thestrainer opposite the dip tube; and a shroud affixed to the dip tubeabove the strainer and the band-pass filter.

Another embodiment described herein takes the form of a gas separatorfor use with a reciprocating pump in a well, comprising: a tube; a plugcapping a lower end of the tube; a sealing coupling attached to an upperend of the tube; a dip tube attached to the sealing coupling, at least aportion of the dip tube positioned within the tube; a strainer at anopposing end of the dip tube from the reciprocating pump; a band-passfilter attached to an end of the strainer opposite the dip tube; and ashroud affixed to the dip tube above the strainer and the band-passfilter and encircling the band-pass filter.

The disclosure also provides a method of treating a fluid, the methodcomprising receiving a fluid from an oil well in a gas separator, thefluid from the well comprising a mixture of a hydrocarbon fluid and agas, producing an at least partially degasified fluid by directing thefluid from the oil well towards a lower end of the gas separator, andproducing a treated fluid by directing the at least partially degasifiedfluid along a flow path between an exterior surface of a band-passfilter of the gas separator and an interior surface of a shroud of thegas separator.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 illustrates a sample gas separator incorporating a shroudedband-pass filter.

FIG. 2 illustrates another sample gas separator incorporating a shroudedband-pass filter.

FIG. 3 illustrates a method for treating a fluid using a shroudedband-pass filter.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

Generally, band-pass filters are used in oil wells and oil fields tohelp alleviate problems associated with paraffin, asphaltenes,emulsions, and certain scales associated with the production of fluidfrom reservoirs. Further, band-pass filters may guide favorable crystalpolymorphism in oil, as well as reducing interfacial tension in oilbetween the constituents of oil and water. In oil wells and fields,band-pass filters stabilize molecular dispersions, and promote molecularsolubility, of numerous constituents of oil. In some cases, theband-pass filter is characterized such that when exposed to a passiveexternal energy source, the band-pass filter oscillates, tuning thefilter to be in resonance with the different types of molecularoscillations pertinent to fluids of interest in oil wells. In someexamples, the band-pass filter is formed at least in part of a suitablemetal alloy.

Many oil wells that use reciprocating pumps to pump oil employ aband-pass filter. The band-pass filter may be positioned upstream fromthe reciprocating pump and in some cases may be included in a down holegas separator. The band-pass filter relies on fluid flowing past it tooperate. However, the fluid flow paths in some conventional down holegas separators at least partially bypass the band-pass filter, therebyreducing its effectiveness. As compared to these conventional down holegas separators, down hole gas separators including a shrouded band-passfilter as described herein can provide a fluid flow path that directsmore of the fluid within the gas separator past the band-pass filter.

Generally, embodiments described herein take the form of down hole gasseparator including a shrouded band-pass filter that ensures liquid flowpast the band-pass filter while reducing or minimizing gas contact withthe band-pass filter. When gas is suspended in the fluid that flows pastthe band-pass filter, the band-pass filter may be less effective andless efficient. Therefore, the shrouded band-pass filters describedherein can also further improve the efficiency of treatment of fluidwithin the gas separator for paraffin, asphaltenes, emulsions, scales,and the like.

The down hole gas separators disclosed herein may be part of anartificial lift system that includes a reciprocating pump. Inembodiments, at least one element of the reciprocating pump moves withinwell tubing positioned within the casing. The well tubing may provide aconduit for fluid from the oil well to be transported to the surface andin some cases may define a barrel of the pump. In some instances, aninlet of the reciprocating pump is positioned downstream of (e.g.,above) the zone where production fluid enters into the casing, alsoreferred to as a fluid entry zone. In some examples, the reciprocatingpump is a sucker pump.

The down hole gas separator may be coupled to an inlet of thereciprocating pump so that treated fluid exiting the gas separatorenters the pump. In some embodiments, the down hole gas separatorincludes a dip tube assembly. In some examples, the dip tube assemblyincludes a dip tube, a band-pass filter coupled to the dip tube, and ashroud at least partially surrounding the band-pass filter. A proximalend of the shroud may be affixed to the dip tube and the shroud mayextend over at least a portion of the band-pass filter to a distal end.The distal end of the shroud may also be referred to as an upstream endof the shroud or a lower end when the dip-tube assembly has a generallyvertical orientation.

The down hole gas separator also typically includes an outer tube atleast partially surrounding the dip tube assembly. The outer tube, whichis also referred to herein simply as a tube or alternately may bereferred to as a housing, may define one or more openings through whichfluid from the oil well enters the gas separator. The outer tube mayalso define one or more vents for gas to exit the gas separator (e.g.,into an annular space between the tubing and the casing). In some cases,the openings through which fluid enters the gas separator also functionas vents for gas to exit the gas separator while in other cases thefluid entering the gas separator may enter through certain openingswhile the gas evacuates through others. The down hole gas separator (oran inlet of the gas separator) may be located downstream from (e.g.,above) the fluid entry zone, within the fluid entry zone, or acombination of these.

As the pump operates, fluid from the oil well is drawn into the tube ofthe gas separator by operation of the pump. The fluid from the oil wellis typically a mixture including gas and a hydrocarbon fluid (e.g.,oil). The fluid entering the gas separator may be directed towards anupstream (e.g., lower) end of the gas separator and may flow between anexterior surface of the shroud and the tube of the gas separator. Whenthe dip tube has a generally vertical orientation, the fluid enteringthe gas separator may fall towards the lower end of the separator. Atleast some of the gas suspended in the fluid that flows into the gasseparator can separate from this fluid as it falls and exit the tubingthrough vents in the tube of the gas separator. Therefore, an at leastpartially degasified fluid can be produced within the gas separator.

In some cases, the presence of the shroud in the gas separator can helpto limit contact between the band-pass filter and gas separated from thefluid. In some cases, a top or upper portion of the shroud may haveholes formed therethrough, also referred to herein as through-holes.These holes may be large enough that gas can pass through the holes butfluid does not. The shroud may be sintered, for example, to defineappropriately sized holes. This may provide more efficient separation ofany gas from fluid within the shroud.

A treated fluid may be produced by directing the at least partiallydegasified fluid along the band-pass filter. The shroud can help toensure flow of the at least partially degasified fluid past theband-pass filter. In some embodiments, the shroud can define a flow pathalong and/or onto the band-pass filter. For example, the shroud maydefine a flow path between an exterior surface of the band-pass filterand an interior surface of the shroud. As an additional example, theshroud may define holes through at least a portion of its body, such alower portion of its body, which define additional flow paths towardsthe band-pass filter. These through-holes may further enhance fluid flowpast the band-pass filter.

The treated fluid may be directed into and through the dip tube and intothe inlet of the reciprocating pump. In some examples, an inlet end ofthe dip tube may define openings to allow the treated fluid to enter thedip tube. In additional examples, the dip tube assembly may also includea strainer positioned between and coupled to the dip tube and theband-pass filter, and the treated fluid may enter the dip tube via thestrainer. The strainer is also positioned within the shroud anddownstream of (e.g., above) the band-pass filter. The dip tube permitsthe treated fluid to flow into the inlet of the reciprocating pump and,ultimately, upward and out of the oil well as the pump operates.

Shrouded band-pass filters may be used with gas separators in an oilwell and generally operate as described above.

These and other embodiments are discussed below with reference to FIGS.1-3 . However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these Figures is forexplanatory purposes only and should not be construed as limiting.

FIG. 1 illustrates a sample gas separator 100 including a shroudedband-pass filter. The view of FIG. 1 is a cross-sectional view showingthe gas separator 100, a reciprocating pump 125, and several elements ofan oil well 105. The gas separator 100 includes features that reduce theamount of solids in the fluid exiting the gas separator as compared tothe fluid entering the gas separator from the well and therefore mayalso be referred to as a mud anchor. The gas separator 100 is positioneddown hole in the oil well 105. The oil well 105 includes a casing 107and a fluid entry zone 109 where fluid from the reservoir 102 can enterthe oil well 105.

The gas separator 100 includes a tube 110 capped by a plug 115 (or, insome cases, a one-way valve), a dip tube 120 in fluid communication withthe pump 125, a strainer 130 at an opposing end of the dip tube 120 fromthe pump 125, a band-pass filter 135 attached to an end of the strainer130 opposite the dip tube 120, and a shroud 140 affixed to the dip tube120 above the strainer 130 and the band-pass filter 135. In other words,the strainer 120 is attached to a lower end of the dip tube when the diptube has a generally vertical orientation. A proximal end of the shroud140 is attached to the dip tube in the example of FIG. 1 . At least aportion of the shroud 140 generally extends downward within the tube 110toward the plug 115 and past an end of the band-pass filter 135. In theexample of FIG. 1 , an upper portion of the shroud extends outward fromthe dip tube and then a lower portion of the shroud extends over part ofthe dip tube, the strainer, and the band-pass filter. The lower portionof the shroud may define an annular space between an interior surface ofthe shroud and an exterior surface of the band-pass filter. In someembodiments, the shroud 140 may terminate such that its end (i.e., itslower end) is coplanar with a portion of the band-pass filter 135 ratherthan extending beyond it.

As shown in the example of FIG. 1 , the reciprocating pump 125 ispositioned within tubing 112 and can move up and down within the tubing112. The seating nipple 150 may snug the pump against the tubing. Insome cases, the attachment of the dip tube 120 to the reciprocating pump125 can cause the gas separator to move up and down the well due to themovement of the reciprocating pump 125.

In additional examples, not all the elements of the reciprocating pump125 travel within the tubing 112 due to the action of the pump.Therefore, the gas separator need not travel up and down the oil well105 when it is coupled to a stationary element of the pump. For example,when the reciprocating pump 125 includes a plunger and a travelingvalve, the plunger and the traveling valve may travel up and down withinthe tubing 112 and a standing valve may remain stationary within thetubing during operation of the reciprocating pump. In such an example,the sealing nipple 150 may retain an inlet to the pump in a fixed andsealed position within the tubing 112, such as through seating of astanding valve defining the inlet on the sealing nipple 150. The sealingnipple 150 may have any form suitable for providing the desired sealingand retention properties for various elements of the pump. In somecases, the tube 110 of the gas separator 100 may be part of the tubing112.

As shown in FIG. 1 , a fluid and gas mixture is drawn from the reservoir102 into the oil well 105 through the fluid entry zone 109. Fluid andgas from the oil well 105 may enter the tube 110 of the gas separator100 through one or more openings 162 in the tube 110 as schematicallydepicted by the arrow. The fluid and gas entering the gas separator 100can fall toward the plug 115, generally through negative pressurecreated by reciprocation of the pump 125 in the oil well 105. As thefluid and gas mixture fills the tube 110, gas may separate and exit thetube through one or more of the openings, as schematically depicted bythe arrow showing gas exiting through the opening 164. Generally, someopenings are higher along the tube wall than others, thus permitting thegas to exit. The gas may exit into a space between the tubing 112 andthe casing 107. The fluid and gas mixture may enter through certainopenings (intake openings) while gas evacuates through others (ventopenings), although this is not necessary. In some cases, the openingsin the tube 110 may have the form of slots.

As the fluid fills the tube 110, it is forced to flow around the shroud140 and thus past the band-pass filter 135 on its way to the strainer130, through which it enters the dip tube 120. The flow of the fluid,which is at least partially degassed, around a lower end of the shroud140 is schematically depicted by the lower curved arrow in FIG. 1 .Thus, the fluid is forced past the band-pass filter 135 by the shroud140 along a fluid flow path schematically depicted by the straight arrowin FIG. 1 . The fluid continues on its way to the strainer 130 and diptube 120, as depicted by a curved arrow, and ultimately its exit fromthe oil well. The fluid flow path past the band pass filter ensures goodcontact between the fluid and the band-pass filter 135, therebyincreasing the efficiency and operation of the band-pass filter intreating the fluid. Further, a significant portion of the gas separatesfrom the fluid within the gas separator prior to the fluid contactingthe band-pass filter 135, again increasing the efficiency andfunctionality of the band-pass filter.

In some embodiments the shroud 140 may have holes/flow paths definedthrough at least a portion of its body. This may permit better fluidflow through the shroud and past the band-pass filter. For example, alower portion of the shroud 140 may be slotted or pierced to definefluid flow paths or otherwise enhance fluid flow.

As yet another option, a top or upper portion of the shroud 140 may haveholes formed therethrough. These holes may be large enough that gas canpass through the holes but fluid does not. The shroud may be sintered,for example, to define appropriately sized holes. This may provide moreefficient separation of any gas from fluid within the shroud.

FIG. 2 illustrates a sample gas separator 200 including a shroudedband-pass filter. The view of FIG. 2 is a cross-sectional view showingthe gas separator 200, a reciprocating pump 225, and several elements ofthe oil well 205. The gas separator 200 is positioned down hole in theoil well 205. The oil well 205 includes a casing 207 and a fluid entryzone 209 where fluid from the reservoir 202 can enter the oil well 205.

The gas separator 200, like the prior-discussed gas separator, includesan external tube 210 capped by a plug 215 (or, in some cases, a one-wayvalve), a dip tube 220 attached to a sealing coupling 245 positionednear one end of a reciprocating pump 225, a strainer 230 at an opposingend of the dip tube 220 from the pump 225, a band-pass filter 235attached to an end of the strainer 230 opposite the dip tube 220, and ashroud 240 affixed to the dip tube 220 above the strainer 230 and theband-pass filter 235. The dip tube 220 is typically in fluidcommunication with the pump 225. As with the gas separator of FIG. 1 ,the shroud 240 generally extends downward within the tube 210 toward theplug 215 and past an end of the band-pass filter 235. In someembodiments, the shroud 240 may terminate such that its end is coplanarwith a portion of the band-pass filter 235 rather than extending beyondit.

In the example of FIG. 2 , the gas separator 200 includes a sealingcoupling 245. The sealing coupling is coupled to the tube 210 as well asthe tubing 212. The sealing coupling 245 may allow gas to flow from alower face of the sealing coupling to a side surface of the sealingcoupling. As an example, the sealing coupling 245 is ported such thatgas may escape the gas separator 200 through the sides, but not throughthe upper face, of the coupling. The sealing coupling may restrict flowof a fluid (e.g., a hydrocarbon liquid) from the lower face to an upperface of the sealing coupling. Fluid, therefore, is directed around theshroud 240 and past the band-pass filter 235 to the strainer 230 asschematically shown by the arrows in FIG. 2 . The shroud 240 thusensures that substantially all fluid passes the band-pass filter,thereby ensuring its efficient operation. Fluid flows past the band-passfilter 235, as schematically depicted by the straight arrow, and intothe strainer 230, as schematically depicted by a curved arrow. The fluidthen flows up along the dip tube 220 and past the sealing coupling 245.The fluid then flows into a chamber associated with the pump 225, whereit is pulled up the oil well 205 to be expelled at the surface. In somecases, the chamber may be positioned below the pump, and in other cases,the chamber may be positioned behind one or more elements of the pump(such as a plunger).

In additional examples, not all the elements of the reciprocating pump225 travel within the tubing 212 due to the action of the pump. Forexample, when the reciprocating pump 225 includes a plunger and atraveling valve, the plunger and the traveling valve may travel up anddown within the tubing 212 and a standing valve may remain stationarywithin the tubing 212. In such an example, the sealing nipple 250 mayretain an inlet to the pump in a fixed and sealed position within thetubing 212 and in some cases may be coupled to the sealing coupling 245.Furthermore, the fluid chamber may be defined between the traveling andthe stationary elements of the reciprocating pump 225. The sealingnipple 250 may have any form suitable for providing the desired sealingand retention properties for various elements of the pump.

In certain embodiments, the gas separator 200 includes intake/ventopenings (e.g., 262, 264) at its upper end (e.g., the end closest to asurface of the oil well) that permit fluid to enter the separator 200during an intake cycle of the pump 225. The openings in the tube 210 maybe similar in function and shape to the openings in the tube 110previously described with respect to FIG. 1 and that description is notrepeated here.

In some embodiments, the gas separator 200 holds approximately fourtimes the volume displayed by the pump 225 during a single intakestroke. In a similar fashion as previously described with respect to thegas separator 100, gas separates from the fluid from the well in theseparator 200 and can leave the separator in the form of bubbles orother exhaust through the openings in the tube 210, prior to fluidreaching the shroud 240. Gas can also leave the separator 200 throughthe sealing coupling 245. As fluid reaches the shroud 240 (or theportion of the tube 210 surrounding the shroud 240), its flow velocityincreases, thereby forcing solids to fall past the shroud towards theplug 215. These solids can discharge into a mud joint (and effectivelyexit the separator system) while the at least partially degassed fluidenters a space between the band-pass filter 235 and the shroud 240. Theat least partially degassed fluid can flow past the band-pass filter andthe fluid so treated can then flow up through the strainer 230, into thedip tube 220 and through the pump 225 to exit the oil well 205.

Accordingly, in the embodiments shown in both FIG. 1 and FIG. 2 , theshroud ensures fluid flows around the band-pass filter instead ofbypassing it, thereby enhancing operation of the band-pass filter.Additional details regarding the construction and operation of theband-pass filter can be found in: U.S. application Ser. No. 16/317,490,filed Jul. 13, 2017; PCT Application No. PCT/US2017/041944, filed Jul.13, 2017; U.S. Provisional Patent Application No. 62/361,654, filed Jul.13, 2016; U.S. Provisional Patent Application No. 62/367,430, filed Jul.27, 2016; and U.S. Provisional Patent Application No. 62/502,016, filedMay 5, 2017, the contents of which are incorporated by reference as iffully disclosed herein.

FIG. 3 illustrates a method for treating a fluid using a shroudedband-pass filter as described herein. The method 300 includes anoperation 310 of receiving a fluid from an oil well in a gas separator.The fluid from the oil well may comprise a mixture of a hydrocarbonfluid and a gas. The operation of receiving the fluid from the oil wellinto the gas separator may comprise receiving the fluid from the oilwell through the opening in a tube of the gas separator. In someembodiments, the opening is located above a fluid entry zone of the oilwell. The tube typically at least partially surrounds the dip tube, theband-pass filter, and the shroud and may be similar to the tubes 110 and210 previously discussed with respect to FIGS. 1 and 2 .

The method 300 further includes an operation 320 of producing an atleast partially degasified fluid. The operation 320 may includedirecting the fluid from the oil well toward a lower end of the gasseparator. As previously discussed, the shroud may limit contact betweenthe band-pass filter and gas separated from the fluid during theoperation of producing the at least partially degasified fluid. Gas mayexit the gas separator through a vent in a tube of the gas separatorduring the operation of producing the at least partially degasifiedfluid. The tube typically at least partially surrounds the dip tube, theband-pass filter, and the shroud and may be similar to the tubes 110 and210 previously discussed with respect to FIGS. 1 and 2 .

The method 300 further includes an operation 330 of producing a treatedfluid by directing the at least partially degasified fluid along a flowpath between an exterior surface of a band-pass filter of the gasseparator and an interior surface of a shroud of the gas separator. Aspreviously discussed, the shroud ensures that fluid flows around theband-pass filter instead of bypassing it, thereby enhancing operation ofthe band-pass filter. In some cases, the action of the band-pass filtermay produce favorable crystal polymorphs and/or reduced interfacialtension between the constituents of oil and water in the treated fluid.

In some embodiments, the method further comprises an operation ofdirecting the treated fluid through a dip tube of the gas separator. Insome examples, the method comprises directing the treated fluid througha strainer of the gas separator and into the dip tube. The treated fluidmay pass through the dip tube and into an inlet of a reciprocating pump.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not intended to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. A gas separator for use with a reciprocating pumpin a well, comprising: a tube; a plug capping a lower end of the tube; adip tube in fluid communication with the reciprocating pump, at least aportion of the dip tube positioned within the tube; a strainer at anopposing end of the dip tube from the reciprocating pump; a band-passfilter attached to an end of the strainer opposite the dip tube; and ashroud affixed to the dip tube above the strainer and the band-passfilter.
 2. The gas separator of claim 1, wherein the shroud extendsdownward within the tube toward the plug and past an end of theband-pass filter.
 3. The gas separator of claim 2, wherein the shrouddefines a fluid flow path past the band-pass filter.
 4. The gasseparator of claim 3, wherein: the fluid flow path is a first fluid flowpath; and the shroud further defines a second fluid flow path into thestrainer.
 5. The gas separator of claim 3, wherein an upper portion ofthe tube defines a gas vent.
 6. The gas separator of claim 3, wherein alower portion of the shroud defines at least one through-hole.
 7. Thegas separator of claim 1, wherein the dip tube is attached to an inletof the reciprocating pump.
 8. A gas separator for use with areciprocating pump in a well, comprising: a tube; a plug capping a lowerend of the tube; a sealing coupling attached to an upper end of thetube; a dip tube attached to the sealing coupling, at least a portion ofthe dip tube positioned within the tube; a strainer at an opposing endof the dip tube from the reciprocating pump; a band-pass filter attachedto an end of the strainer opposite the dip tube; and a shroud affixed tothe dip tube above the strainer and the band-pass filter and encirclingthe band-pass filter.
 9. The gas separator of claim 8, wherein thesealing coupling allows gas to flow from a lower face of the sealingcoupling to a side surface of the sealing coupling.
 10. The gasseparator of claim 9, wherein the sealing coupling restricts flow of ahydrocarbon fluid from the lower face to an upper face of the sealingcoupling.
 11. The gas separator of claim 8, wherein a lower portion ofthe shroud defines an annular space between an interior surface of theshroud and an exterior surface of the band-pass filter.
 12. The gasseparator of claim 11, wherein an upper portion of the shroud extendsoutward from the dip tube to the lower portion of the shroud.
 13. Thegas separator of claim 8, wherein the dip tube is in fluid communicationwith an inlet to the reciprocating pump.
 14. The gas separator of claim8, wherein the gas separator further includes a mud joint.
 15. A methodof treating a fluid, the method comprising: receiving a fluid from anoil well in a gas separator, the fluid from the oil well comprising amixture of a hydrocarbon fluid and a gas; producing an at leastpartially degasified fluid by directing the fluid from the oil welltoward a lower end of the gas separator; and producing a treated fluidby directing the at least partially degasified fluid along a flow pathbetween an exterior surface of a band-pass filter of the gas separatorand an interior surface of a shroud of the gas separator.
 16. The methodof claim 15, wherein the shroud limits contact between the band-passfilter and gas separated from the fluid during the operation ofproducing the at least partially degasified fluid.
 17. The method ofclaim 15, wherein: the method further comprises directing the treatedfluid through a strainer of the gas separator and into a dip tube of thegas separator.
 18. The method of claim 17, wherein: gas exits the gasseparator through a vent in a tube of the gas separator during theoperation of producing the at least partially degasified fluid, the tubeat least partially surrounding the dip tube, the band-pass filter, andthe shroud.
 19. The method of claim 17, wherein: the operation ofreceiving the fluid from the oil well into the gas separator comprisesreceiving the fluid from the oil well through an opening in a tube ofthe gas separator, the tube at least partially surrounding the dip tube,the band-pass filter, and the shroud and the opening located above afluid entry zone of the oil well.
 20. The method of claim 15, furthercomprising an operation of directing the treated fluid through a diptube of the gas separator and into an inlet of a reciprocating pump.